Method of de-molding a plurality of golf balls or golf ball precursor products from injection mold assembly

ABSTRACT

A method and assembly for molding golf balls is disclosed herein. The invention includes an injection mold assembly ( 20 ) with a first mold half ( 22   a ) having a plurality of cavities and at least one locating pin ( 92 ) and a second mold half ( 22   b ) having a plurality of cavities and at least one aperture for engagement with the at least one bushing ( 94 ) and a spring ( 250 ) for exerting a lateral force against the second mold half ( 22   b ). Preferably, the locating pin has a first taper section ( 93 ) and a second taper section ( 95 ). Preferably, the bushing ( 84 ) has a first cavity 1( 115 ) and a second cavity ( 117 ).

CROSS REFERENCES TO RELATED APPLICATIONS

The Present application is a continuation of U.S. patent applicationSer. No. 12/132,055, filed on Jun. 3, 2008 now U.S. Pat. No. 7,591,972,which is a divisional application of U.S. patent application Ser. No.10/711,206, filed on Sep. 1, 2004, now U.S. Pat. No. 7,381,041.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and method for de-moldinga golf ball from a mold cavity.

2. Description of the Related Art

Golf balls may comprise one-piece constructions or they may includeseveral layers including a core, one or more intermediate layers and anouter cover that surrounds any intermediate layer and the core. Inmulti-component golf balls, there exists an inner core. Often, this coreis made by winding a band of elastomeric material about a sphericalelastomeric or liquid-filled center. Alternatively, the core may be aunitary spherical core made of a suitable solid elastomeric material.One such material that is conventionally used for the core of golf ballsis a base rubber, such as polybutadiene, which is cross-linked with ametal acrylate, such as zinc diacrylate.

In the construction of some multi-component golf balls, an intermediateboundary layer is provided outside and surrounding the core. Thisintermediate boundary layer is thus disposed between the core and theouter cover of the golf ball.

Located outwardly of the core and any intermediate boundary layer is acover. The cover is typically made from any number of thermoplastic orthermosetting materials, including thermoplastic resins such asionomeric, polyester, polyetherester or polyetheramide resins;thermoplastic or thermoset polyurethanes; natural or synthetic rubberssuch as balata (natural or synthetic) or polybutadiene; or somecombination of the above.

The cover may be injection molded, compression molded, or cast over thecore. Injection molding typically requires a mold having at least onepair of mold cavities, e.g., a first mold cavity and a second moldcavity, which mate to form a spherical recess. In addition, a mold mayinclude more than one mold cavity pair.

In one exemplary injection molding process each mold cavity may alsoinclude retractable positioning pins to hold the core in the sphericalcenter of the mold cavity pair. Once the core is positioned in the firstmold cavity, the respective second mold cavity is mated to the first toclose the mold. A cover material is then injected into the closed mold.The positioning pins are retracted while the cover material is flowableto allow the material to fill in any holes caused by the pins. When thematerial is at least partially cured, the covered core is removed fromthe mold.

As with injection molding, compression molds typically include multiplepairs of mold cavities, each pair comprising first and second moldcavities that mate to form a spherical recess.

Although the prior art has disclosed many methods of manufacturing golfballs, the prior art has failed to provide an efficient manufacturingprocess at a lower cost. The present invention overcomes the increasedcosts of the prior art by implementing an improved injection mold andde-molding process for a lower cost mass production process.

BRIEF SUMMARY OF THE INVENTION

One aspect of the present invention is an injection mold assembly forgolf balls which includes a first mold half, a second half and a springfor exerting a lateral force against the second mold half duringdisengagement of the first mold half from the second mold half. Thefirst mold half has a plurality of cavities and a first pin having abase with a first diameter and a first taper section with a diametersmaller than the first diameter. The second mold half has a plurality ofcavities and a first bushing for engagement with the first pin of thefirst mold assembly. The first bushing has a main cavity with a firstdiameter and a first cavity with a diameter smaller than the diameter ofthe main cavity.

Another aspect of the present invention is a method for de-molding aplurality of golf balls or golf ball precursor products from aninjection mold assembly. The method beings with injecting a polymermaterial into a plurality of cavities of a mold to form a layer for agolf ball. Next, a lateral force is exerted on the second mold half.Next, the first mold half is separated from the second mold half. Next,the second mold half is laterally displaced from the first mold half.

Having briefly described the present invention, the above and furtherobjects, feature and advantages thereof will be recognized by thoseskilled in the pertinent art from the following detailed description ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a side view of a mold assembly of the present invention

FIG. 2 is a top plan view of the first mold half of the mold assembly ofFIG. 1.

FIG. 3 is a side plan view of the first mold half of FIG. 2.

FIG. 4 is a top plan view of a second mold half of the mold assembly ofFIG. 1.

FIG. 5 is a side plan view of the second mold half of FIG. 4.

FIG. 6 is an isolated view of a preferred embodiment of a locating pinof the present invention.

FIG. 6A is top plan view of the locating pin of FIG. 6.

FIG. 6B is top perspective view of the locating pin of FIG. 6.

FIG. 7 is an isolated view of an alternative embodiment of a locatingpin of the present invention.

FIG. 7A is top plan view of the locating pin of FIG. 7.

FIG. 7B is top perspective view of the locating pin of FIG. 7.

FIG. 8 is an isolated view of a bushing of the present invention.

FIG. 8A is top plan view of the bushing of FIG. 8.

FIG. 9 is an exploded view of a pair mold inserts and golf ballprecursor product utilized for the mold assembly of the presentinvention.

FIG. 10 is a side view of a mold assembly as utilized within aninjection molding machine.

FIG. 11 is a top plan view of the second mold half and spring assemblyof the present invention.

FIG. 12 is an isolated view of a locating pin within a bushing of themold assembly of the present invention at the beginning of theseparation of the first mold half from the second mold half during ade-molding process.

FIG. 13 is an isolated view of a locating pin within a bushing of themold assembly of the present invention at an intermediate step of theseparation of the first mold half from the second mold half during ade-molding process.

FIG. 14 is an isolated view of a locating pin within a bushing of themold assembly of the present invention near the end of the separation ofthe first mold half from the second mold half during a de-moldingprocess.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1-5, a mold assembly for injection molding a layer ofa thermoplastic material on a golf ball precursor product is generallydesignated 20, and is composed of a first mold half 22 a and a secondmold half 22 b. In a preferred embodiment, the first mold half 22 a isthe top mold half and the second mold half 22 b is the bottom mold half.The mold halves 22 a-b are mated together during the injection moldingprocess.

Referring again to FIGS. 1-5, each mold half 22 a-b is generallycomposed of a solid body 70. Each body 70 is preferably composed of ametal material, and most preferably composed of stainless steel. Each ofthe mold halves 22 a-b preferably has a plurality of insert apertures 33for preferably housing each of a plurality mold inserts 30. Preferably,the insert apertures 33 each have a diameter that ranges from 2.00inches to 3.00 inches, and the diameter of each insert aperture ispreferably larger than the diameter of the corresponding mold insert 30.

The first mold half 22 a preferably has a plurality of locatingapertures 74 a-d at each corner. A plurality of locating pins 92 a-b arepreferably mounted within two of the plurality of locating apertures 74a-d. In a most preferred embodiment, locating pin 92 a is mounted withinlocating aperture 74 a and locating pin 92 b is mounted within locatingaperture 74 d.

The second mold half 22 b preferably has a plurality of locatingapertures 74 f-h at each corner. A plurality of locating bushings 94 a-bare preferably mounted within two of the plurality of locating apertures74 f-h. In a most preferred embodiment, locating bushing 94 a is mountedwithin locating aperture 74 g and locating bushing 94 b is mountedwithin locating aperture 74 f.

The locating pins 92 a-b and locating bushings 94 a-b properly align themold halves 22 a-b during mating thereof to form the mold assembly 20.In a preferred embodiment, each of the plurality of locating pins 92 a-bis diagonally opposed to each other on the first mold half 22 a, andeach of the plurality of locator bushings 94 a-b is diagonally opposedto each other on the second mold half 22 b.

As shown in FIGS. 6, 6A and 6B, a preferred embodiment of the locatingpin 92 has a first taper 93 section, a second taper section 95, a base99 and a base flange 101. The locating pin 92 preferably has a flat top107. The base flange 101 has a shoulder 105 to lock the locating pinwithin an aperture 74. The base 99 has a shoulder 103. The first tapersection 93 is preferably tapered at an angle, α_(T1) ranging from 30 to70 degrees relative to the shoulder 103 of base 99, and most preferablytapered at an angle of 45 degrees relative to the shoulder 103 of thebase 99. The second taper section 95 is preferably tapered at an angle,α_(T2), ranging from 50 to 85 degrees relative to the shoulder 103 ofbase 99, and most preferably tapered at an angle of 75 degrees relativeto the shoulder 103 of the base 99.

Each locating pin 92 has a length Lp preferably ranging from 1.5 inchesto 4.0 inches, and most preferably a length of 2.3 inches. The baseflange 101 has a length, “Lf”, preferably ranging from 0.025 inch to0.500 inch, and most preferably from 0.175 inch to 0.200 inch. The base99 has a length, “Lb”, preferably ranging from 0.75 inch to 2.0 inches,and most preferably a length of 1.25 inch. The second taper section 95has a length, “L_(T2)”, preferably ranging from 0.100 inch to 0.500inch, and more preferably from 0.200 inch to 0.300 inch. The first tapersection 93 has a length, “L_(T1)”, preferably ranging from 0.250 inch to1.00 inch, and most preferably from 0.500 inch to 0.750 inch.

As shown in FIG. 6A, the base flange 101 has a radius, “R_(F)”,preferably ranging from 0.500 inch to 1.00 inch, and most preferably0.75 inch to 0.90 inch. The base 99 has a radius, “R_(B)”, preferablyranging from 0.400 inch to 0.95 inch, and most preferably 0.60 inch to0.70 inch. The second taper section 95 has a radius, “R_(T2)”,preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35inch to 0.50 inch. The second taper section 95 has a radius, “R_(T2)”,preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35inch to 0.50 inch. R_(T1) and R_(T2), respectively, represent thelargest radius of the first taper section 93 and the second tapersection 95. The radius, if measured at other locations along each of thetapered section 93 and 95 will be smaller than R_(T1) and R_(T2).

In an alternative embodiment shown in FIGS. 7, 7A and 7B, the locatingpin 92′ has a cylindrical section 97 positioned between a first tapersection 93′ and a second taper section 95. In this embodiment, thelocating pin 92 also has a base 99, a base flange 101, a flat top 107, ashoulder 105 and a shoulder 103. The first taper section 93′ ispreferably tapered at an angle, α_(T1), ranging from 30 to 70 degreesrelative to the shoulder 103 of base 99, and most preferably tapered atan angle of 45 degrees relative to the shoulder 103 of the base 99. Thesecond taper section 95′ is preferably tapered at an angle, α_(T2),ranging from 50 to 85 degrees relative to the shoulder 103 of base 99,and most preferably tapered at an angle of 75 degrees relative to theshoulder 103 of the base 99.

Each locating pin 92′ has a length Lp preferably ranging from 1.5 inchesto 4.0 inches, and most preferably a length of 2.3 inches. The baseflange 101 has a length, “Lf”, preferably ranging from 0.025 inch to0.500 inch, and most preferably from 0.175 inch to 0.200 inch. The base99 has a length, “Lb”, preferably ranging from 0.75 inch to 2.0 inches,and most preferably a length of 1.25 inch. The second taper section 95′has a length, “L_(T2)”, preferably ranging from 0.250 inch to 0.750inch, and more preferably from 0.550 inch to 0.650 inch. The cylindricalsection 97 has a length, “Lc”, preferably ranging from 0.400 inch to 1.0inch, and most preferably a length ranging from 0.600 inch to 0.850inch. The first taper section 93′ has a length, “L_(T1)”, preferablyranging from 0.080 inch to 0.150 inch, and most preferably from 0.100inch to 0.130 inch.

As shown in FIG. 7A, the base flange 101 has a radius, “R_(F)”,preferably ranging from 0.500 inch to 1.00 inch, and most preferably0.75 inch to 0.90 inch. The base 99 has a radius, “R_(B)”, preferablyranging from 0.400 inch to 0.95 inch, and most preferably 0.60 inch to0.70 inch. The second taper section 95′ has a radius, “R_(T2)”,preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35inch to 0.50 inch. The second taper section 95 has a radius, “R_(T2)”,preferably ranging from 0.30 inch to 0.60 inch, and most preferably 0.35inch to 0.50 inch. R_(T1) and R_(T2), respectively, represent thelargest radius of the first taper section 93′ and the second tapersection 95′. The radius, if measured at other locations along each ofthe tapered section 93′ and 95′ will be smaller than R_(T1) and R_(T2).

As shown in FIGS. 8 and 8A, a bushing 94 has a first diameter, “D1”, asecond diameter, “D2”, and a third diameter “D3.” The first diameter,D1, preferably has a diameter that ranges from 0.100 inch to 0.750 inch,and most preferably ranging from 0.350 inch to 0.500 inch. The seconddiameter, D2, preferably has a diameter that ranges from 1.0 inch to1.750 inches, and most preferably ranging from 1.250 inches to 1.50inches. The third diameter, D3, preferably has a diameter that rangesfrom 1.250 inches to 2.0 inches, and most preferably ranging from 1.50inches to 1.750 inches. The bushing 94 preferably has a length Lbu,ranging from 1.0 inch to 2.0 inches, and most preferably from 1.25inches to 1.50 inches.

FIG. 9 illustrates a preferred pair of mold inserts 30 that are usedwith the mold assembly 20 of the present invention. Each mold insert 30preferably has a hemispherical cavity 32 within a body 34. The body 34preferably has an annular flange 36 that has an alignment flat 38 alonga portion thereof. The flange 36 is preferably used for mounting eachmold insert 30 within a mold half 22.

The hemispherical cavity 32 preferably has an inverse dimple patternthereon if a cover is formed on the golf ball precursor product 25 inthe mold insert 30. Alternatively, the hemispherical cavity 32 will havea smooth surface if a boundary layer is formed on the golf ballprecursor product 25 in the mold insert 30. Support pins 28 arepreferably configured to support the golf ball precursor product 25 in apredetermined position within a mold cavity. Each mold half 22 a-bincludes a series of gates and a network of feeder lines, not shown, forcarrying the injectable material into the cavities of each of the moldinserts 30 during the manufacturing process.

Preferred injectable materials include thermoplastic and reactioninjection moldable materials. Preferred thermoplastic materials includeionomers and polyurethanes. Preferred reaction injection moldablematerials include polyurethanes such as disclosed in U.S. Pat. No.6,699,027, which pertinent parts are hereby incorporated by reference.

FIG. 10 illustrates the mold assembly 20 as utilized within an injectionmolding machine. The first mold half 22 a is mounted to an upper frame222 and the second mold half is mounted to a base 224. A spring assembly250 exerts pressure on the second mold half 22 a during the de-moldingprocess as explained below. The pressure exerted by the spring isadjusted by an adjuster 255. FIG. 11 is a top plan view of the secondmold half 22 b within the base 224. The second mold half has a first end300 and a second end 302, and the spring assembly 250 exerts pressure ona first end 300 of the second mold half 22 b. In a preferred embodiment,the spring assembly exerts a pressure preferably ranging from 300 to 500pounds per square inch. However, those skilled in the pertinent art willrecognize that a greater or lesser pressure may be utilized withoutdeparting from the scope and spirit of the present invention.

FIGS. 12-14 illustrate the operation of the locating pins 92 during thede-molding process. In FIG. 12, the locating pin 92 is completely withina bushing 94. The first taper section 93 within a first cavity 115 ofthe bushing 94, the second taper section 95 within a second cavity 117of the bushing 94 and a portion of the base 99 is within a third cavity119 of the bushing 94.

As shown in FIG. 13, the first mold half 22 a further separates from thesecond mold half 22 b, preferably vertically. During the separation, thespring assembly 250 exerts a constant lateral pressure on the secondmold half 22 b. As the locating pin 92 is separated from the bushing 94,the first taper section 93 and second taper section 95 allow for arelatively smooth transition with the first taper section 93 moving fromthe first cavity 115 to the second cavity 117 and the second tapersection 95 moving from the second cavity 117 to the third cavity 119.During this separation, the second mold half 22 b moves laterally inrelation to the first mold half 22 a. In a preferred embodiment, thelateral distance moved by the second mold half 22 b relative to thefirst mold 22 a is the radius R1, which is half the diameter, D1, of thefirst cavity 115 of the bushing 94. This preferred lateral movement adistance R1 occurs during the separation, preferably verticalseparation, a distance L_(T1), the length of the first taper section 93.The distance L_(T1) preferably corresponds to the depth of the firstcavity 115.

As shown in FIG. 14, the first mold half 22 a further separates from thesecond mold half 22 b, preferably vertically. Again, during theseparation, the spring assembly 250 exerts a constant lateral pressureon the second mold half 22 b. As the locating pin 92 is furtherseparated from the bushing 94, the first taper section 93 allows for arelatively smooth transition with the first taper section 93 now movingfrom the second cavity 117 to the third cavity 119. During thisseparation, the second mold half 22 b again moves laterally in relationto the first mold half 22 a. In a preferred embodiment, the lateraldistance moved by the second mold half 22 b relative to the first mold22 a is the radius R2, half the diameter, D2, of the second cavity 117minus R1. This preferred lateral movement a distance R2-R1 occurs duringthe separation, preferably vertical separation, a distance L_(T2), thelength of the second taper section 95. The distance L_(T2) preferablycorresponds to the depth of the second cavity 117.

Although not shown, as the locating pin 92 completely separates from thebushing 94, the second mold half 22 b will laterally move due to thefull extension of the spring assembly 255.

The present invention allows for an easier separation of the mod halves22 a-b during de-molding and also allows for a separation of the newlymolded golf ball or golf ball precursor product from a hemisphericalcavity of each of the mold inserts 30.

From the foregoing it is believed that those skilled in the pertinentart will recognize the meritorious advancement of this invention andwill readily understand that while the present invention has beendescribed in association with a preferred embodiment thereof, and otherembodiments illustrated in the accompanying drawings, numerous changes,modifications and substitutions of equivalents may be made thereinwithout departing from the spirit and scope of this invention which isintended to be unlimited by the foregoing except as may appear in thefollowing appended claims. Therefore, the embodiments of the inventionin which an exclusive property or privilege is claimed are defined inthe following appended claims.

1. A method for de-molding a plurality of golf balls or golf ballprecursor products from an injection mold assembly, the methodcomprising: injecting a polymer material into a plurality of cavities ofa mold to form a layer for a golf ball, the mold comprising a first moldhalf and a second mold half engaged together, the first mold half havinga first pin comprising a base with a first radius, a first taper sectionwith a second radius smaller than the first radius, a second tapersection with a third radius smaller than the second radius, and thefirst mold half having a second pin having a base with a first radius, afirst taper section with a second radius smaller than the first radius,and a second taper section with a third radius smaller than the secondradius, the second mold half having a first bushing with a main cavityhaving a main cavity with a first diameter, a first cavity with a seconddiameter smaller than the first diameter of the main cavity, and asecond cavity with a third diameter smaller than the second diameter,the first pin of the first mold half engaged within the first bushing ofthe second mold half, the second mold half having a second bushing forengagement with the second pin of the first mold assembly, the secondbushing having a main cavity with a first diameter, a first cavity witha second diameter smaller than the first diameter of the main cavity,and a second cavity with a third diameter smaller than the seconddiameter; exerting a lateral force on the second mold half by a springassembly wherein the spring assembly exerts pressure on the second moldhalf ranging from 300 to 500 pounds per square inch; separating thefirst mold half from the second mold half, wherein the first mold halfis separated from the second mold half along a vertical axis; andforcing the second mold half to be laterally displaced from the firstmold half along a horizontal axis perpendicular to the vertical axis. 2.The method according to claim 1 wherein injecting a polymer materialcomprises injecting a reaction injection polyurethane material.
 3. Themethod according to claim 1 further comprising separating the first moldhalf from the second mold half a first vertical distance correspondingto a length of the second cavity and laterally moving the second moldhalf from the first mold half a first lateral distance.
 4. The methodaccording to claim 3 wherein the first lateral distance corresponds tothe remainder of the second radius of the first cavity of the firstbushing minus the third radius of the second cavity of the firstbushing.
 5. The method according to claim 3 further comprisingseparating the first mold half from the second mold half a secondvertical distance corresponding to a length of the first cavity of thefirst bushing and laterally moving second mold half from the first moldhalf a second lateral distance.
 6. The method according to claim 5wherein the second lateral distance corresponds to the remainder of thefirst radius of the main cavity of the minus the second radius of thefirst cavity of the first bushing.